This report forms the fourth annual analysis of pollution incident statistics in England and Wales. Summary statistics are provided on substantiated incidents that occurred in 1993, including commentary on court actions that took place in respect of these incidents together with details of some of the more notable prosecutions. Pollution is categorised into five fundamental sources: agriculture, industry, sewage and water-related, transport and "other". The basic types of incidents are defined as oil, sewage, chemical, organic wastes and "other". Incidents are also categorised according to severity of environmental impact with Category 1 the most severe to relatively minor impact in Category 3. Examples of pollution prevention initiatives carried out during 1993 are described and where discrete data are available, the most important types and sources of pollution are highlighted. This will enable the NRA to utilise current and future resources in the most effective way by targeting notable pollution problem areas.